1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a computer-readable recording medium for processing an intraluminal image that is a captured image of an intralumen.
2. Description of the Related Art
Conventionally, endoscopes are widely used as a medical observation device of a type that is introduced inside a body of an examinee such as a patient and observes the inside of a lumen of the body. In addition, recently, an eating-type endoscope (capsule endoscope) is developed in which an imaging device, a communication device transmitting image data imaged by the imaging device outside the body in a wireless manner, and the like are provided in a capsule-type casing. Since observation and diagnosis using an image of the inside of a lumen (intraluminal image) that is imaged with the medical observation device requires abundant experience, a medical diagnosis supporting function that supports the diagnosis of a doctor is desired. As one of image recognition technologies for realizing such a function, a technology is proposed which automatically detects an abnormal portion such as a lesion from an intraluminal image and presents the abnormal portion to a medical doctor or others.
For example, in Japanese Laid-open Patent Publication No. 2002-99896, a technology is disclosed in which candidates for a microcalcification shading that is one feature of a cancerous portion of breast cancer are stably detected by using a shape-dependent filter regardless of a coarse structure or a linear structure. In Japanese Laid-open Patent Publication No. 2002-99896, a second shape-dependent filter is prepared in advance, of which filter characteristics are optimized in accordance with various conditions such as photographing conditions, reading conditions, image contrast, and the size of a microcalcification shading, combined conditions thereof, or the like based on the supposed shape of the microcalcification shading. Then, a microstructure image representing a microstructure potion is generated by eliminating a linear structure formed inside the image by using a first shape-dependent filter that is a morphology filter (for example, Kohata et al., “Extraction of Microcalcification Image Through Morphology Filter Using Multiple Structure Element”, The Institute of Electronic, Information, and Communication Engineers Journal, D-II, Vol. J75-D-II, No. 7, P 1170 to 1176, July 1992 or Kohata et al., “Basics of Morphology and Application to Mammogram Processing”, Medical Imaging Technology, Vol. 12, No. 1, January 1994). Thereafter, by performing an enhancement process using the prepared second shape-dependent filter with respect to the microstructure image, the enhanced image is generated in which only the candidates for the microcalcification shading are enhanced more than the periphery thereof (a portion other than candidates for the microcalcification shading, including a coarse structure portion, a linear structure portion, and the like that could not be eliminated by the first shape-dependent filter).